1. Field
The present invention relates to an input device.
2. Description of Related Art
For example, a keyboard packaged with or connected to computer equipment or the like has a plurality of key tops for respective characters to be inputted. The key tops are arranged at predetermined positions in rows and columns so as to be adjacent to each other on the keyboard.
Recently, the computer equipment and the keyboard itself have become smaller and smaller. In a case of corresponding to the trend of miniaturization, it is required to decrease key pitches between the respective key tops arranged on the keyboard (spacing between the centers of two keys).
However, when the key pitches are decreased, the finger movement is restricted. As a result, a key that corresponds to a character to be inputted (hereinafter, this will be referred to as ‘target key’) and a key arranged in the vicinity of the target key (hereinafter, this will be referred to as ‘adjacent key’) may be pushed down simultaneously or consecutively. This should be avoided since when the adjacent key is pushed down, incorrect inputs and/or incorrect operations of keys will occur easily.
For the purpose of preventing incorrect operations and/or incorrect inputs, in a known keyboard, a protruding part to restrict the moving range of a finger is formed on each key top, so that the finger will be moved linearly only in a predetermined movement direction (see for example, JP 2003-84887 A).
In another known keyboard, the shape of the key tops in the right-hand area is differentiated from that of the key tops in the left-hand area, considering the operability for each of the right hand and the left hand (see for example JP 2003-140807 A).
Furthermore, for the purpose of decreasing the size without sacrificing the operability, in another known keyboard, key tops are slid so that two different switches can be operated selectively with a single key (see for example JP H07-65673 A).
In a case of forming a protruding part on the upper face of a key top as disclosed in for example JP 2003-84887 A, incorrect inputs and/or incorrect operations of adjacent keys located near the protruding part can be prevented at the time of inputting the target key. However, incorrect inputs of the adjacent keys located opposite to the protruding part side cannot be prevented, because at the side without the protruding parts, the target key and the adjacent key may be pushed down simultaneously or consecutively.
In a case where the shape of the key tops in the right-hand area are differentiated from that in the left-hand area as disclosed in JP 2003-140807 A for example, when the key pitches in either the right-hand area or the left-hand area is decreased, the target key and any of the adjacent keys may be pushed down simultaneously or consecutively. This will cause a problem in that incorrect inputs and/or incorrect operations cannot be prevented.
Furthermore, in a case where a key top is slid so that one key can operate selectively two different switches, it is required to move the fingers for inputting different keys. As a result, the target key and any of the adjacent keys may be pushed down simultaneously or consecutively. As a result, incorrect inputs and/or incorrect operations cannot be prevented.
For preventing the user's finger from contacting with an adjacent key at the time of pushing down a target key, the surface area of the operation surface of the key top to be pushed can be decreased simply (for example, it can be shaped circular). However, when the surface area of the operation surface is decreased excessively, problems may occur. For example, the decrease in the contact area between the operation surface and the finger degrades the operability at the key touch. Furthermore, the region for printing characters corresponding to the keys become smaller, and the visibility will be degraded.